Optically clear and antistatic pressure sensitive adhesives

Abstract

The present invention is directed to an antistatic pressure sensitive adhesive. The antistatic pressure sensitive adhesive comprises a pressure sensitive adhesive, and an antistatic agent comprising at least one organic salt. Certain embodiments of the antistatic pressure sensitive adhesive also have a luminous transmission of greater than about 89% according to ASTM D 1003-95. Additional embodiments of the antistatic pressure sensitive adhesive have a haze of less than about 5% according to ASTM D 1003-95, and in specific embodiments the haze is less than about 2% according to ASTM D 1003-95.

1 . An antistatic pressure sensitive adhesive comprising 
 (a) a pressure sensitive adhesive; and    (b) an antistatic agent comprising at least one organic salt,    wherein the antistatic pressure sensitive adhesive has a luminous transmission of greater than about 89% according to ASTM D 1003-95 and the organic salt comprises a cation comprising an organic substituent and a weakly coordinating anion comprising an organic substituent.    
   
   
       2 . The antistatic pressure sensitive adhesive of  claim 1  wherein the antistatic agent comprises a non-polymeric or polymeric organic nitrogen, sulfonium or phosphonium onium cation and a weakly coordinating organic anion.  
   
   
       3 . The Antistatic pressure sensitive adhesive of  claim 1  wherein the luminous transmission is greater than 90% according to ASTM D 1003-95.  
   
   
       4 . The antistatic pressure sensitive adhesive of  claim 1  wherein the adhesive has a haze of less than about 5% according to ASTM D 1003-95.  
   
   
       5 . The antistatic pressure sensitive adhesive of  claim 1  wherein the adhesive has a haze of less than about 2% according to ASTM D 1003-95.  
   
   
       6 . The antistatic pressure sensitive adhesive of  claim 1  wherein the organic salt is present in at least about 5% by weight of the antistatic pressure sensitive adhesive.  
   
   
       7 . The antistatic pressure sensitive adhesive of  claim 1  wherein the organic salt is present in at least about 10% by weight of the antistatic pressure sensitive adhesive.  
   
   
       8 . The antistatic pressure sensitive adhesive of  claim 1  wherein the organic salt is present in at least about 30% by weight of the antistatic pressure sensitive adhesive.  
   
   
       9 . The antistatic pressure sensitive adhesive of  claim 1  wherein the adhesive has a surface resistivity of less than about 1×10 13  Ohms/Square.  
   
   
       10 . The antistatic pressure sensitive adhesive of  claim 1  wherein the adhesive has a surface resistivity of less than about 1×10 11  Ohms/Square.  
   
   
       11 . The antistatic pressure sensitive adhesive of  claim 1  wherein the antistatic agent is a compound represented by the formula  
       (R 1 ) t-v G + [(CH 2 ) q OR 2 ] v X −   wherein    R 1  comprises alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, or alicyclicaryl moieties,    R 2  comprises hydrogen or alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, or alicyclicaryl moieties,    G is nitrogen, sulfur or phosphorous,    if G is sulfur then t is 3, if G is nitrogen or phosphorous then t is 4,    if G is sulfur then v is an integer of 1 to 3, if G is nitrogen or phosphorous the v is an integer of 1 to 4,    q is an integer of 1 to 4, and    X is the weakly coordinating organic anion.    
   
   
       12 . The antistatic pressure sensitive adhesive of  claim 1  wherein the antistatic agent is a compound represented by the formula  
       (R 1 ) t-v G + [(CH 2 ) q R 2 ] v X −   wherein    R 1  comprises alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, or alicyclicaryl moieties,    R 2  comprises hydrogen or alkyl, alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralkyl, aralicyclic, or alicyclicaryl moieties,    G is nitrogen, sulfur or phosphorous,    if G is sulfur then t is 3, if G is nitrogen or phosphorous then t is 4,    if G is sulfur then v is an integer of 1 to 3, if G is nitrogen or phosphorous the v is an integer of 1 to 4,    q is an integer of 1 to 4, and    X is the weakly coordinating organic anion.    
   
   
       13 . The antistatic pressure sensitive adhesive of  claim 1  wherein the weakly coordinating anion is a compound represented by one of the following formulae:  
     
       
         
         
             
             
         
       
     
     wherein  
     R 6  is independently a fluorinated alkyl or aryl group that may be cyclic or acyclic, saturated or unsaturated,  
     Q is independently an SO 2  or a CO linking group, and  
     Y is QR 6 , CN, halogen, H, alkyl, aryl, Q-alkyl, or Q-aryl.  
   
   
       14 . The antistatic pressure sensitive adhesive of  claim 10  wherein the weakly coordinating anion is  − N(SO 2 CF 3 ) 2 .  
   
   
       15 . The antistatic pressure sensitive adhesive of  claim 1  wherein the pressure sensitive adhesive is selected from those based on natural rubbers, synthetic rubbers, styrene block copolymers, polyvinyl ethers, poly(meth)acrylates, polyolefins, silicones, or combinations thereof.  
   
   
       16 . The antistatic pressure sensitive adhesive of  claim 1  wherein the cation is a compound represented by one of the following formulae:  
     
       
         
         
             
             
         
       
     
       + N[(R 4 ) 4-d ][(POA)R 5 ] d    
     wherein,  
     n is an integer of 3 to 50,  
     b is an integer of 5 to 150,  
     a is an integer from 0 to 5,  
     c is an integer from 0 to 5, where a+c is an integer from 2 to 5,  
     A is a CH≡, CH 3 C≡, CH 3 CH 2 C≡, or a —CH 2 -CH—CH 2 - group,  
     x, y and z, equal or different, are integers of 1 to 30 such that the sum of x+y+z≧5,  
     POA is either a homopolymer or a copolymer that is random, blocked, or alternating, and POA comprises 2 to 50 units represented by the formula ((CH 2 ) m CH(R 3 )O) where m is independently an integer from 1 to 4,  
     R 3  is independently hydrogen or a lower alkyl group comprising 1 to 4 carbon atoms,  
     R 4  is independently an alkyl, an alicyclic, an aryl, an alkalicyclic, an arylalicyclic, or an alicyclicaryl group,  
     R 5  is independently hydrogen, an alkyl, an alicyclic, an aryl, an alkalicyclic, an arylalicyclic, or an alicyclicaryl group, and  
     d is an integer from 1 to 4.  
   
   
       17 . The article of  claim 1  wherein the antistatic agent is a compound represented by one of the following formulae: 
 1,3-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide:    [CH 3 -cyc-(N + C 2 H 2 NCH)CH 2 CH 3 ] [ − N(SO 2 CF 3 ) 2 ],    1,3-ethylmethylimidazolium nonafluorobutanesulfonate: [CH 3 -cyc-(N + C 2 H 2 NCH)CH 2 CH 3 ] [ − OSO 2 C 4 F 9 ],    1,3-ethylmethylimidazolium trifluoromethanesulfonate: [CH 3 -cyc-(N + C 2 H 2 NCH)CH 2 CH 3 ] [ − OSO 2 CF 3 ],    dodecylmethyl-bis(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide: [C 12 H 25 N + (CH 3 )(CH 2 CH 2 OH) 2 ] [ − N(SO 2 CF 3 ) 2 ]   1,2-dimethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide,    1,2-dimethyl-3-propylimidazolium tris(trifluoromethanesulfonyl)methide,    1,2-dimethyl-3-propylimidazolium trifluoromethanesulfonyl perfluorobutanesulfonylimide,    1-ethyl-3-methylimidazolium cyanotrifluoromethanesulfonylamide,    1-ethyl-3-methylimidazolium bis(cyano)trifluoromethanesulfonylmethide,    1-ethyl-3-methylimidazolium trifluoromethanesulfonylperfluorobutanesulfonylimide,    octyldimethyl-2-hydroxyethylammonium trifluoromethylsulfonylperfluorobutanesulfonylimide,    1-butylpyridinium trifluoromethylsulfonylperfluorobutanesulfonylimide,    1-ethyl-2-methylpyrazolium perfluorobutanesulfonate,    1-butyl-2-ethylpyrazolium trifluoromethanesulfonate,    N-ethylthiazolium bis(trifluoromethanesulfonyl)imide,    N-ethyloxazolium bis(trifluoromethanesulfonyl)imide,    1-butylpyrimidinium perfluorobutanesulfonylbis(trifluoromethanesulfonyl)-methide, and mixtures thereof.    
   
   
       18 . An adhesive article comprising 
 (a) a backing having at least one major surface; and    (b) the antistatic pressure sensitive adhesive of  claim 1  on the major surface of the backing,    wherein the adhesive article has a luminous transmission of greater than about 88% according to ASTM D 1003-95.